Secure Deletion on Log-Structured File Systems

The authors address the problem of secure data deletion on log-structured file systems. They focus on the YAFFS file system, widely used on Android smartphones. They show that these systems provide no temporal guarantees on data deletion and that deleted data still persists for nearly 44 hours with average phone use and indefinitely if the phone is not used after the deletion. Furthermore, they show that file overwriting and encryption, methods commonly used for secure deletion on block-structured file systems, do not ensure data deletion in log-structured file systems.